I've had the dreaded OD light flashing, bad shifts and code 452 for a while. Finally decided to fix it. Read a lot that a new VSS won't fix it but for $15 decided it was worth a try. Actually looking the signal requires an oscilloscope and I don't have one. New VSS didn't fix it. Decided to look at PSOM. Read a lot about replacing resistor, capacitors, diodes and checking for bad solder joints. I know a fair bit about electronics and replacing components that aren't know to be bad is like throwing a new VSS at it without knowing for sure lol. Resistors rarely fail on their own and if they do fail it is usually apparent because the burn out. It's usually another component that causes a resistor to fail. Diode? Maybe but easy to test. Caps? Sure but usually bad ones are bulging. Everything on the PSOM looked great. I put it under a microscope to check for bad solder joints. It all looked ok. Decided to resolder anyway. I touched everything except the surface mount stuff. Put the PSOM back in and did a test drive. Problem gone. Half a dozen drives now and still ok. I wish I would have just reseated all the connectors on the PSOM and did a test drive but too late. My suggestion is if your speedo works but still bad shifts/code 452 is to check VSS connector, reseat the PSOM and connectors before doing anything else. Next try resoldering if you are able. Once all that is done and problem persists then start throwing money at it.

 

Quite often the problem is in the wiring harness. Why not diagnose that?

 

Sure that's smart.